The present invention relates generally to liquid level detecting and indicating systems, and more particularly to a liquid level detector with a resistor whose resistance is changed in accordance with liquid level variation. This invention is applicable particularly, but not exclusively, to fuel level indicators of motor vehicles.
Various types of indicating systems have been devised heretofore to detect and indicate the level of a liquid within a receptacle and, of these systems, a resistance-changing type liquid level indicator as is known in the art is so constructed that detection of the liquid level is made on the basis of the resistance change of a resistor depending upon liquid level variation. An important problem in such a type of liquid level indicator is that a pointer is severely vibrated in response to rapid variation of the liquid level and difficulty is encountered to accurately recognize the liquid level. Generally, a motor vehicle is subject to inclination or vibration due to rough road surfaces and hence the fuel level within the fuel tank is violently varied in response to, the inclination or vibration. This may cause an inaccurate indication of the fuel level, resulting in a disadvantage to the vehicle driver. One known arrangement for solution of this problem is that a delay circuit is provided between a liquid level detecting section and an indicating section of the liquid level indicating system and its delayed amount is varied in accordance with the magnitude of the liquid level vibration for prevention of the pointer vibration due to the liquid level vibration, as exemplified in description in Japanese Utility Model Publication No. 59-37699. However, since this arrangement is basically made with the delay circuit being provided between a liquid level sensor and a fuel gauge, one problem arises in that the delay of fuel indication is always performed and this makes difficult quick indication of the fuel level. To avoid this problem associated with the provision of the delay circuit, a bypass device may be required to directly couple the liquid level sensor to the fuel gauge so that a detection signal from the liquid level sensor does not pass through the delay circuit, resulting in a complex construction.